The Rot Doctor


Subject: rot
Date: Thu, 25 Oct 2001

I am still restoring my 37' Viking and I noticed the rot seemed to be greater where the wood came into contact with metal, such as the bolts that support the prop shafts and where screws are screwed into ribs. Why is that? Also, does CPES have a shelf life? My friend has some that has to be at least a couple years old.

The reason for the greater rot around the metal is because 1) metal will heat and cool faster than wood and in the process condense more moisture out of the atmosphere, 2) metallic salts sometimes will increase the vulnerability of the wood to fungal and bacterial activity, as well as deteriorate wood on their own merits, and 3) the metal fasteners often provide water with greater access to the wood . Kind of depends on what metal, where it is, and the degree of possible electrolytic activity going on in the boat. It's a common problem. Epoxying the wood will help a lot.

CPES does not have a shelf life, assuming it has been stored unmixed with the tops screwed shut, and that it has not been exposed to prolonged freezing temperatures. We are still testing a batch from 1990 and it works just fine.

When you apply CPES to these areas, make sure they are reasonably dry, and at the same time examine them for the degree of porosity. If the wood is very soft and porous, you should either apply multiple coats of CPES, or follow the CPES application (after a few days or longer) with our Layup & Laminating Resin, a very slow setting resin which will gradually seep into the wood and fill the larger vacancies.

Come on back if you have additional questions.